diff --git a/ethcore/light/src/client/header_chain.rs b/ethcore/light/src/client/header_chain.rs
index 1c218204b..d4ea8d107 100644
--- a/ethcore/light/src/client/header_chain.rs
+++ b/ethcore/light/src/client/header_chain.rs
@@ -119,7 +119,7 @@ impl Decodable for Entry {
 }
 
 fn cht_key(number: u64) -> String {
-	format!("canonical_{}", number)
+	format!("{:08x}_canonical", number)
 }
 
 fn era_key(number: u64) -> String {